The present invention provides Anacardium sp. specific genomic DNA sequence and the methods for utilization of these sequences in detection of Cashew husk in tea samples. Particularly this invention relates to a very sensitive, accurate and efficient method of identification of Anacardium occidentale (cashew) species. More particularly, the method is designed to detect presence of any part of cashew plant including the dried and ground apple in market samples of made tea.
The main application of this invention is to detect the adulteration of loose as well as branded tea by any part of cashew plant (and thus can be part of quality control measures) in addition to the taxonomical authentication of cashew plants.
Tea is a non-alcoholic beverage with consumption through out the world. It is produced by processing youngest two leaves and a bud of a plant [Camellia sinensis (Linn). O Kuntze] of family Theaceae (Wight, W., 1959, Nature, 8317: 26-28; Banerjee, B., 1988, Nature (London), 332: 580). It is mainly produced in India, China, Srilanka, Kenya and Japan (Singh, I. D., 1979, Two and A Bud, 26: 23-26), rest of the world procures tea from these producing countries. There is an increasing trend of consumer market for tea in India and abroad. Although tea production has increased world wide, for example, in India it has increased from 320 million Kg in 1960 to 870 million kg in 1988 (Anonymous, 1999-I, Contemporary Tea Time, 8(3): 31), there seems to be limit to meet the world demand. Tea is a health drink and is popular due to its stimulatory properties. It is also a physiological function modulating drink and is reported to act against a number of abnormalities including artherosclerosis, radiation damage, antioxidative, anticancer, antiulceric, antiviral, germicidal etc (Chen, Z., 1999, In xe2x80x9cGlobal Advances in Tea Sciencexe2x80x9d edited by N K Jain, Publishers: Aravali Books International (P) Ltd., New Delhi. pp333-358). It has been reported that sometimes leaves, husks, barks and other parts of some plants are used as substitute and/or adulterants of tea, for example Acacia arabica (Babul or kikar) bark after being used in tanning hide is converted into a powder resembling tea and is sold as such in market (Israel, A. H. and Issar, R. K., 1973, Indian J Pharmacy, 35: 208-209). In a survey conducted by Sudershan and Bhat (Sudershan, R. V. and Bhat, R. V., 1995, J. Food Sci. Technol., 32(5): 368-372), 8 adulterants of tea namely cashew husk, iron fillings, colour, blackgram husk, other foreign leaves, exhausted tea leaves and saw dust were reported in 9% of the samples collected from various state food laboratories of India. Acer negundo, Adiantium cappillus veneris, Albizia amara, Chenopodium ambrosioides, Epilobium angustifolium and Fragaria vesca leaves have also been reported to be used in some tea either as substitute or adulterants (Garg, S., 1992, In Substitute and Adulterant Plants, Ist Edn. pp. 136-142, Published at xe2x80x9cPeriodical Experts Book Agencyxe2x80x9d, New Delhi). Powdered animal hide has also been reported to be mixed with dry tea and sold in open market on cheaper rates (Anonymous, 1999-II, Divya Himalchal, 22 July). In another survey of 25 loose tea samples collected randomly from different parts of India, 80% were found adulterated with foreign vegetables, saw dust, sand, stones, stalk and used tea leaves (Anonymous, 1999-III, The Assam Review and Tea News, 87: 28-29). Adulteration leads to health risks to the society, since many of these adulterants are carcinogenic and many adulterant plants have side effects. Although intense surveys needs to be done not only on loose tea available in the market but also on branded tea, there is sufficient evidence about the adulteration of made tea. There is an intense need to identify adulterants in tea, which is not possible, many a times by visual inspection or by measuring only ash values. There are currently no methods available to identify the adulteration of tea for many of the above said adulterants. Use of molecular tools in such cases could be ideal, specially, when most of the adulterants are biological substances. During processing the tea, degrades much of the cells and their DNA, and only the degraded DNA can be isolated (Singh, M., Bandana and Ahuja, P. S., 1999, Plant Mol. Biol. Reporter, 17 and 171-78), it can be suitable only for PCR based techniques. Recently conserved sequences including 5S rRNA genes and their spacer length variability has been utilized to differentiate fungal species (Moukhamedov, R. S., Hu, X., Nazar, R. N. and Robb, J., 1994, Phytopathology, 83: 256-259), to identify the plant varieties (Martsinkovskaya, A. I., Moukhamedov, R. S., and Abdukarimov, A. A., 1996, Plant Mol. Biol. Reporter, 14: 44-49) and to detect cereal composition in admixtures (Ko, H. L. and Henry, R. J., 1996, Plant Mol. Biol. Reporter, 14 (1): 33:43). Using the same approach, we have cloned and sequenced the spacer regions between 5S rRNA genes in 3 plants species and have developed a protocol to utilise the sequence differences to detect the adulteration of cashew husk in dry market tea samples by Polymerase Chain Reaction.
The main objective of the present invention is to provide a species-specific DNA sequence and its utilization in detection of Anacardium occidentale. 
Another object of this invention is to provide a PCR based method to detect adulteration of tea by cashew husk or any other part of cashew plant.
The present invention provides Anacardium sp. specific genomic DNA sequence and the methods for utilization of these sequences in detection of Cashew husk in tea samples. This invention relates to a very sensitive, accurate and efficient method of identification of Anacardium occidentale (cashew) species. Particularly, the method is designed to detect presence of any part of cashew plant including the dried and ground apple in market samples of made tea.
The main application of this invention is to detect the adulteration of loose as well as branded tea by any part of cashew plant (and thus is a part of quality control measures) in addition to the taxonomical authentication of cashew plants.